THE BIONOMICS OF CONVOI-UTA ROSCOFFENSIS. 877 



active. In Convoluta it is so inactive that no surplus of 

 carbohydrate is stored as starch. 



It is also noteworthy that the starch-formation in the blue 

 region is in Convoluta very considerable, more so apparently 

 than in green plants (see Pfeffer, 1900, p. 390). We may 

 di-aw a further conclusion from these facts, namely, that the 

 infecting organism — if infecting organism there be — is a 

 member of the Chlorophycea3 (green algas), and not of the 

 Cyanophyce^ (blue-green algte), since in the former group 

 the assimilatory maximum is as in Convoluta, between B 

 and C, whereas in the latter group it is between C and D (in 

 the yellow). (Pf offer, 1902, vol. i, p. 344.) 



The spectrum of an extract of Convoluta chlorophyll 

 shows, even when examined by a hand-spectroscope, the 

 absorption band most characteristic of chlorophyll (between 

 B and C Fraunhofer lines), as well as the absorption at the blue 

 end from about midway between E and F. Faint indications 

 of the other bands characteristic of chlorophyll at the red end 

 of the spectrum were observed. There can, therefore, be no 

 question but that the pigment of Convoluta contains 

 chlorophyll. Moreover, as is the case with ordinary green 

 chromatophores of plants, the chlorophyll of Convoluta 

 occurs side by side with carotin, which latter substance may 

 be detected by the usual tests — for example, by the bright 

 blue colour resulting from the addition of concentrated 

 sulphuric acid to the dried tissues. 



4. Appendix. — Assimilation of Starch by Convoluta 

 roscoffensis in White and Monochromatic Light. 



In the first experiment young Convoluta 1 mm. long 

 were used. They were collected on the shore August 27th, and 

 put in darkness to deplete (August 28th). On September 2nd 

 they were found to be starch-free, and were then placed in 

 glass vessels under screens, transmitting liglit as follows : — 

 Red screen (a selected piece of ruby glass) transmits from B 

 almost to D (Fraunhofer lines; 0"5 — 2'5of Browning's direct 



